#include <iostream>
using namespace std;
struct node{
	char data;
	struct node *lch,*rch;
};
node *c(char data){
	node *newnode=new node;
	newnode->data=data;
	newnode->lch=newnode->rch=0;
	return newnode;
}
void post(node *root){
	if (root!=NULL){
		post(root->lch);
		post(root->rch);
		printf("%c",root->data);
	}
}
int main(){
	node *root=c('-');
	root->lch=c('+');
	root->rch=c('/');
	root->lch->lch=c('a');
	root->lch->rch=c('*');
	root->rch->lch=c('e');
	root->rch->rch=c('f');
	root->lch->rch->lch=c('b');
	root->lch->rch->rch=c('-');
	root->lch->rch->rch->lch=c('c');
	root->lch->rch->rch->lch=c('d');
	post(root);
	return 0;
	
	
	
	

}
